Localization devices have been developed to assist surgeons in performing surgical procedures. When utilized in a procedure, markers that can be tracked by a stereoscopic camera system are attached to bones. The stereoscopic camera system is connected to a data processing system that records the positions of the markers in space to establish a coordinate reference system relative to each bone bearing a marker. Additional markers may be attached to surgical tools and the localization device programmed with the location of the working portion of the surgical tool relative to the marker. The tool may then be used to palpate (touch) specific landmarks on the bones while the localization device records their location in order to ascertain the position of the landmarks in the coordinate reference systems of the bones. A monitor is used to display information developed from the coordinate reference system and the landmarks for use in guiding a surgeon during the procedure, such as navigating another surgical tool to a particular location in the coordinate reference system.
Typically, the surgical tool used to palpate points on a bone is a pointer. The marker can be mounted on the pointer in only one predetermined way. As noted, the localization device is programmed with data indicating the position of the working portion, e.g., the tip, of the pointer relative to the marker. By observing the marker, the localization device can determine the pointer tip position.
The accuracy of the pointer tip position as determined by the localization device is dependent on several factors. These factors include proper mounting of the marker on the pointer, accurate programming of the data indicating the position of the pointer tip relative to the marker, and trueness of the marker and the pointer. If any of these factors are amiss, the pointer tip position as determined by the localization device will be inaccurate, which, in turn, will result in the development of erroneous information that may be used to guide a surgeon during a surgical procedure. If the information used to guide the surgeon is erroneous, the surgical procedure may be affected adversely. Thus, there is a need to verify the accuracy of points palpated using the localization device to prevent the development of erroneous information based on the palpated points. The present invention fulfills this need among others.